pvl_est_Rs_IEC60891_2

PVL_EST_RS_IEC60891_2 Estimate Rs using method 2 of IEC60891.

Contents

Syntax

Rs = pvl_est_Rs_IEC60891_2(IVCurves, aIsc, bVoc)

Description:

Method 2 in IEC60891 translates a point on an IV curve measured at irradiance G1 and cell temperature Tc1 to the corresponding point on an unobserved IV curve at irradiance G2 and cell temperature Tc2. The translation reduces the voltage value by a voltage drop across the ‘internal series resistance’ of the module ([IEC 60891], Eq. 2). The resistance Rs is found by an iterative search over a set of IV curves measured at different irradiance levels and constant cell temperature: first, current for each IV curve is translated linearly to a common irradiance, then a fitting parameter is found by translating Voc to a common value, and finally Rs is found by minimizing the variance of Pmp of the translated IV curves. Method 2 differs from Method 1 by allowing greater variation in irradiance among the IV curves.

pvl_est_Rs_IEC60891_2 assumes that the IV curves are measured at, or have been translated to a common cell temperature.

Inputs:

Outputs:

Example

clearvars

% Set up parameters for a representative 60 cell cSi module using the Desoto model
Const.q = 1.60218E-19;
Const.k = 1.38066E-23;
Const.E0 = 1000;
Const.T0 = 25;

param.aIsc = 0.0008;  % A/C
param.bVoc = -0.1900; % V/C

param.Rs_ref = 0.2;
param.Rsh_ref = 1000;
param.IL_ref = 8.0;
param.I0_ref = 5e-10;

param.a_ref = 1.05 * 60 * Const.k/Const.q * (273.15 + Const.T0);

EgRef = 1.121;
dEgdT = -0.0002677;

% Calculate set of IV curves
Ee = 900:20:1100;
Tc = 25;
nPts = 100;
for i=1:length(Ee)
    [IL, I0, Rs, Rsh1, nNsVth] = pvl_calcparams_desoto(Ee(i), Tc, param.aIsc, param, EgRef, dEgdT);
    IVcurves(i) = pvl_singlediode(IL, I0, Rs, Rsh1, nNsVth, nPts);
end

% Add Ee and Tc to IVcurves
for i=1:length(Ee)
    IVcurves(i).Ee = Ee(i);
    IVcurves(i).Tc = Tc;
end

% Calculate relative temperature coefficients

STC_Isc = IVcurves(6).Isc;
STC_Voc = IVcurves(6).Voc;
aIsc_rel = param.aIsc / STC_Isc;
bVoc_rel = param.bVoc / STC_Voc;

% Estimate Rs and a
[Rs, a] = pvl_est_Rs_IEC60891_2(IVcurves, aIsc_rel, bVoc_rel)
Rs =

    0.1996


a =

    0.0428

References:

See also

pvl_est_kappa_IEC60891_2, pvl_translate_IV_curve_IEC60891_2

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